1. Field of the Invention
This invention relates to an electrophotographic photosensitive material having a photoconductive layer on an electrically conductive substrate, as well as to a process for producing said electrophotographic photosensitive material.
2. Description of the Prior Art
As electrophotographic photosensitive materials, there are generally employed photosensitive materials consisting of an electrically conductive substrate such as aluminum, iron, their alloys or the like having thereon an inorganic photoconductive layer consisting of amorphous selenium, Se-Te alloy or In-sensitized amorphous selenium or Se-Te alloy, or an organic photoconductive layer. Usually, this type of photosensitive material is used in a process for the formation of an image comprising subjecting the surface of a photosensitive material to charging, image exposure and development by the Karison process on its surface, and optionally transferring the toner image formed by the development onto paper or the like.
In such a process, the photoconductive film is mechanically injured in the step of transferring the developed toner image to paper or the like or in the step of removing the toner remaining on the surface of photosensitive material by means of a brush or the like. However, because of the low hardness of the selenium constituting the photoconductive film, scuff marks are formed on the surface of photoconductive layer every time these steps are repeated. As a result, crystallization of selenium takes place at the part of scuff marks to make the charging difficult, so that the difference of potential necessary for electrophotography becomes impossible to obtain and the print becomes indistinct.
In Japanese Patent Application Kokai (Laid-Open) No. 87,155/80, there is proposed a photosensitive material provided with a photoconductive amorphous silicon layer for improving the abrasion resistance of photoconductive material such as CdS, ZnO, Cd-Te or the like. In U.S. Pat. No. 4,225,222 there is mentioned a technique for forming a layer of amorphous silicon having hydrogen on the surface of a drum. All these known techniques are grounded on the utilization of amorphpus silicon as a photoconductive layer. However, amorphous silicon is so poor in film-formability that about one day is necessary for forming a photoconductive amorphous silicon by a chemical decomposition-deposition process (CVD process) or a sputtering process. Further, amorphous silicon is low in sensitivity to rays having a long wave length such as semiconductor laser ray, though it is high in sensitivity to He-Ne gas laser or He-Ce laser ray, both of which have a short wave length.